TECHNOLOGIES OF ALUMINA-MAGNESIA REFRACTORIES FOR STEEL LADLES PART I, BRICK DEVELOPMENT

摘要

In this article, technologies of unbumed Al_2O_3-MgO (UAM) refractories are demonstrated in terms of microstructure evolution. During operation, Mg~(2+) diffuses from MgO to Al_2O_3 through the liquid phase to form spinel (MgAl_2O_4) network. Molten slag tends to penetrate along the voids in the spinel network structure and spinel dissolves in the penetrated slag. Therefore, maintaining a high degree of spinel saturation in the penetrated molten slag is important. In order to achieve the condition described above, suppression of overall mass transfer through penetrated slag is effective. This is achievable by evolution of complicated spinel network structure with small pore diameter, which increases the flow resistance of molten slag. Thus, optimization of refractory composition and fabricating conditions, with the aim of creating on improved spinel network, is essential. The effectiveness of spinel network improvement was validated by commercial appiications. According to the investigation of UAM brick after use, further densification due to heating under restrained conditions was recognized. Hence, it was concluded that the evolution of the spinel network structure in UAM refractories is essential technology needed to improve durability.